$authentication .= $authentiction. $1. " ";

##</code><code>##

$authentication .= $authentication. $1. " ";

##</code><code>##

   while ($str =~/authentication ?(\S+)?/g){
      $authentication .= $authentiction. $1. " "; #more perlish
   }

##</code><code>##

  $authentication = join " ", $str =~ /authentication ?(\S+)?/g; #even more perlish